In a double-blind trial, 327 patients (57 men) over 65 (mean age 79.5) years received all possible combinations of calcium carbonate 3 g, vitamin D3 1000 iu, methandienone 2.5 mg and/or placebos daily for 9 months. The higher incidence of bone fractures in the placebo group was not significant. Serum calcium, phosphorus, creatinine, aspartate aminotransferase and alkaline phosphatase were followed: the greatest changes occurred with methandienone, which thus reduced osteoporotic activity and increased the muscular mass most effectively; calcium carbonate had the poorest effect. Surprisingly, coronary mortality was higher among those taking all three active substances. With two treatments the increase was not significant, but when both the groups receiving a combination of any two of the treatments were compared with those taking only one or neither of these two treatments, a significant increase in coronary deaths was seen, most significant (P less than 0.001) in those receiving vitamin D3 and methandienone.